Mad Rivers (or Why Rivers Usually from North to South)

Rivers always follow gravity and go down hill.

It has nothing to do with the equator

It has nothing to do with following north to south

There are no more complex reasons behind it than they always go downhill

Something I found in the bowels of the interwebs
"The Earth is spherical, and so no direction is really more "up" or "down" than any other, no matter where you are on the planet. And water (from which rivers are made, of course) cannot flow "up". Water flows in only one direction: down. The important thing to remember is that to a river, or more precisely to the drops of water that make up the river, "down" has nothing to do with compass points -- with latitude or longitude -- only with altitude. Water flows from higher altitudes to lower ones, and the river's channel has to be steep enough to overcome not only gravity and inertia, but also friction between water currents. Otherwise, you get a lake."